The present invention pertains to a continuously operating, self-propelled apparatus for open cast mining and testing the minability of mineral raw materials and rock veins with properties that are critical from the viewpoint of separation and passing on in surface mining according to the preamble of the principal claim. It is preferably used as a testing apparatus (auxiliary apparatus) for the simple and inexpensive determination of the optimal apparatus parameters as the basis for the adaptation of a surface miner (final apparatus) to the specific geological conditions of a new field of use, but it is also suitable for use as a small, simple surface miner for small deposits of mineral raw materials and for exposing these raw materials.
According to Ref. No. DE 199 41 799.7 [U.S. patent application Ser. No.: 09/385,944), a surface miner with a roller-shaped mining member has been known for the selective mining of mineral raw materials occurring in sedimentary beds and for exposing these raw materials. It comprises a substructure with a three-track (caterpillar) chassis; the superstructure with the drive container and the driver stand is arranged on the substructure. The milling roller module, comprising the transverse frame, the milling roller and the takeup chute, is rigidly fastened to the superstructure in front of the three-caterpillar chassis in the direction of travel, which is also the direction of mining. The discharge belt, which is followed by the loading belt arranged pivotably on the superstructure, is located behind the milling roller module in the area of the substructure and the superstructure in the direction in which the separated material is conveyed. To adjust the height of the milling roller in relation to the track level and consequently to set the depth of milling, lifting cylinders are provided as adjusting members on both sides between the substructure and the superstructure. The lifting cylinders can be actuated independently from one another. Due to the rigid arrangement of the milling roller module on the superstructure, the depth of milling during the first cut into a block being mined and during moving out of this block being mined is changed due to the change in the height of the superstructure. Since the apparatus always travels on the freshly cut level during the mining operation due to the milling roller being arranged in front of the chassis, the cutting circle diameter formed by the milling tools in the block being mined is again brought into the middle position during the mining operation, so that the apparatus will mine a uniform block height. If it is necessary to bring the milling roller into an oblique position in relation to the track level at right angles to the direction of travel; this can be achieved by means of a different actuation of the lifting cylinders. Smooth run of the milling roller is achieved due to the stable and robust design of the apparatus even in the case of hard materials to mine.
The parameters of the apparatus, such as the size of the apparatus, the output of the drives and the speed of cutting and feed of the surface miner are determined based on the intended mining output. The number and the arrangement of the cutting tools as well as of the material guiding and material ejection means on the circumference of the milling roller and the cutting tools themselves are selected as a function of the properties of the material to be mined and the requirements imposed on the particle size of this material. The service life of the tools plays an important role as well.
If a surface miner is to be prepared for use in an area that has critical properties different from those of the hitherto known areas of use and the specific requirements on the apparatus cannot be derived empirically, the foreseeably necessary drive output is first determined, the geometry of the milling roller is set and the most suitable tools are selected on the basis of theoretical knowledge and practical experience. Experience gained under comparable conditions of use is taken into account as well. However, corrections will be made if it is found during the trial run that the apparatus was not adjusted optimally. In the simplest case, better results can be obtained even with different tools, which can be easily replaced as expendable parts. However, the necessary changes can be achieved in the extreme case only by converting the apparatus, e.g., by equipping it with a different milling roller and with more powerful drives. The costs for this increase linearly with the size, the performance capacity and the technical furnishing of the apparatus.
The causes for the uncertainties in the adaptation of a surface miner to the specific conditions of use are that these conditions may be very extreme and multifaceted. The practical applications can never be simulated 100% even in laboratory tests.
The basic object of the present invention is therefore to develop a simple apparatus with which trials concerning the behavior during the use of the machine (vibrations, noise, cutting behavior and wear resistance) can be performed directly at the site of use for highly differentiated applications. These data obtained with the testing apparatus shall then be embodied in the surface miner which is larger and is also better equipped technically. As a small surface miner of a simple design, the apparatus shall be suitable for removing rock veins and for mining mineral raw materials of small thickness.
This object is accomplished with a testing apparatus with which the same working movements relevant for the mining operation can be performed, in principle, as with the surface miner to be optimized, but which is smaller and has a simpler design and is therefore substantially lighter and can thus be transported at a low cost to each site of use being considered and can be used there.
According to the invention an apparatus for open cast mining and testing the cutting minability of critical material is provided with a track (caterpillar type) chassis, an apparatus frame with a drive unit as well as a driver stand and a milling roller. The milling roller is arranged in front of the chassis in the direction of travel and rotates around a horizontal axis of rotation at right angles to the direction of travel. The milling roller operates with undershot and can be raised and lowered. The milling roller extends over the entire width of the apparatus and is equipped with cutting tools, guide plates and ejection plates. The milling roller is in functional connection with a ring chute. The overall weight, the drive output and the throughput of the apparatus (testing apparatus) are lower than those of the surface miner (final apparatus) at a defined ratio. However, the circumferential velocity of the said cutting tools and the force acting on the cutting tool are the same, and the speed of rotation of the roller and the rate of feed can be varied continuously to optimize the mining output.
To obtain usable data for the surface miner (final apparatus), certain premises must be met. Thus, the overall weight, the drive output and the throughput of the testing apparatus must be smaller than those of the surface miner at a defined ratio, but the force acting on the cutting tool (cutter) must be the same. To ensure that the force acting on a cutting tool is approximately equal to that acting in the final apparatus, the circumferential velocity of the milling roller and the rate of feed of the testing apparatus can be varied continuously.
The adjusting device adjusts the height and the transverse slope of the milling roller in relation to the level. This is achieved with only two lifting cylinders. Different depths of cut can be obtained by simply pivoting the milling roller by means of the adjusting cylinder. It is necessary to change the transverse slope of the milling roller when deposits of mineral raw materials are to be exposed or opened whose surface is sloped at right angles to the direction of feed or arched. The mining technology makes provisions for the axis of the milling roller to be positioned in parallel to the level after the elimination of the transverse slope during the removal of all further subjacent beds.
Straight-shank cutters are provided for equipping the milling roller with cutting tools. They are available in various shapes, degrees of hardness and materials. The suitability of various materials of the cutter cap and its heating as well as the resistance of the basic material of the cutter to wear are evaluated during the testing of the straight-shank cutters. The cutter holders are provided with bushings, by which the cutter holders are protected from wear and the rotary movement necessary for uniform wear and the self-sharpening effect of the straight-shank cutters is facilitated. These bushings are also expendable parts and can be replaced when needed. To increase the availability of the surface miner (final apparatus), tests are also carried out with the testing apparatus with the aim of increasing the service life of these bushings and consequently the interval at which they must be replaced.
Since the number of cutting tools must also be reduced in the testing apparatus of reduced size compared with the final apparatus in order to obtain comparable results, the cutting tools are arranged in only one helical line. By changing the speed of rotation of the roller and the rate of feed, the same force acting on the cutting tools is obtained as in the final apparatus.
The separated material is deposited between the two individual caterpillars of the chassis and loaded on trucks.
The operation of a large surface miner (final apparatus) can be simulated and tested with a testing apparatus of such a design under the special conditions of use at the site of use. Based on the reduction of the size of the apparatus compared with the surface miner and the reduction of the total weight, the drive output and the throughput at a constant ratio, which is to be determined, and the equal speed of cutting and the equal cutting force, the test results can be applied to the final apparatus.
Various tests can be performed to optimize the apparatus and to increase the output due to the fact that the speed of cutting and the rate of feed can be changed with the specific design of the testing apparatus and individual parts that are significant with respect to the output and the wear can be replaced and adapted. The implementation of the test results in the surface miner (final apparatus) is simpler and less expensive than in the case of the subsequent testing and optimization of a surface miner.
The testing apparatus can also be used as a surface miner. This applies especially to the opening and mining of smaller deposits of mineral raw materials.
Further details and advantages of the subject of the present invention will appear from the following description and the corresponding drawings, in which a preferred exemplary embodiment of an apparatus is shown, which is especially suitable for use as a testing apparatus for the optimal adaptation of a surface miner (final apparatus) to specific conditions of use, but can also be used as a surface miner.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.